High Sierra Topix

Experienced Sierra Nevada backpackers have over decades been aware of how ridiculously inaccurate some USGS topographic map dashed black line hiking trail elements have been. I won't go into a list of reasons that is so. Since GPS tracking devices arose, more accurate trail lines have been possible, especially when used with satellite imagery. My brief input herein is for those planning trips, a way to reduce that issue is to use caltopo dot com in the below modes that will show both the USGS dashed lines and GPS track paths. This can be especially confusing at trail junctions and places a trail crosses streams. There are also websites with GPS tracking captures from individuals one could also use.

In the upper right caltopo Map Layers pane, select Scanned Topos. In the Map Overlays pane select MapBuilder Overlay. Below shows how incorrect that looks from Mineral King to Sawtooth Pass:
https://caltopo.com/map.html#ll=36.451 ... &b=t&a=mba

Next switch from Scanned Topos to NAIP, that shows the satellite view. Toggle back and forth MapBuilder Overlay. Zoom in + twice. That will show how the red line is atop or nearly atop the trail where such is visible. Note in forest trails are less visible.

Here is one more example on the Rock Creek to Pioneer Basin trail that happens to be where I have a tentative trip planned for this summer. Having been there in the past, recall being especially confused about the lower Golden Creek trail and junctions and how the trail up to the Trail Lakes has lots of switchbacks that are not shown on the topo's thus is significantly more distance than it appears.

https://caltopo.com/map.html#ll=37.4455 ... &b=t&a=mba

This looks like endless hours of fun...And a big storm is on the way. Thanks for the entertainment!

SSSdave wrote: ↑Mon Mar 08, 2021 1:48 pm Since GPS tracking devices arose, more accurate trail lines have been possible, especially when used with satellite imagery.

Possible, but unfortunately not (easily) automatable. Most individual GPS tracks are not very accurate. Aggregated tracks are pretty accurate but loose detail in tight switchbacks or along steep canyons. Satellite projections also have alignment error that varies quite a bit. Fixing these tracks in OpenStreetMap is a mostly manual effort guided by GPS tracks, aggregations, satellite and USFS/USTopo imagery. Ultimately it's not perfect but it should be more accurate than the USGS topos and USFS maps. After trails are updated it takes a number of months before these are reflected in CalTopo.

Most, if not all, major trails in Yosemite, SEKI, Sierra/Sequoia/Inyo NF have been updated in the last six months and the majority should be on CalTopo by now. A good chunk of Humbolt-Toiyabe, Stanislaus and El Dorado too.

In this particular case (and since I was the one who update it) it was hand traced it using the fall 2020 Strava heatmap to get in the right area and ESRI World Image Clarity imagery (locally aligned) for smaller details. It looks like this in the jOSM editor:

Most, if not all, major trails in Yosemite, SEKI, Sierra/Sequoia/Inyo NF have been updated in the last six months and the majority should be on CalTopo by now. A good chunk of Humbolt-Toiyabe, Stanislaus and El Dorado too.

The updates you are referring to are in OpenStreetMap? I have taken to using it in GAIA as it oftentimes has more accurate detail and has trails and items missing from scanned maps. Not that it is always accurate either. It has the additional advantage of being vector-based, thus taking up less room on the iPhone. I generally consider the satellite images too large to download for trail use.

I get many inquiries for GPS tracks every year, which I do send to people but with the warning to only use a track as one piece of information. Yes, the tracks are usually very accurate, but my particular path choice may have been influenced by snow or water or some other factor.

CAMERONM wrote: ↑Wed Mar 10, 2021 6:55 am The updates you are referring to are in OpenStreetMap? I have taken to using it in GAIA as it oftentimes has more accurate detail and has trails and items missing from scanned maps.

Yep, in OpenStreetMap.

CAMERONM wrote: ↑Wed Mar 10, 2021 6:55 am I get many inquiries for GPS tracks every year, which I do send to people but with the warning to only use a track as one piece of information. Yes, the tracks are usually very accurate, but my particular path choice may have been influenced by snow or water or some other factor.

From what I can tell the USFS does just this when updating their actual trail maps... the tracks may generally be pretty accurate and then deviate (sometimes by a lot) to clear early season snow, deadfall, or whatever. Other times when there is no longer a trail they'll still update it with an arbitrary recorded route. While this generally improves things over the older USGS quads it's hit or miss.

Here's a marginally useful update near Taboose. Black dashed line is from the old FS maps (the really old ones stop in the valley), gray dashed line is from the new TrailNFS database. From satellite it looks like it follow an old trail for a while then goes for a cross country loop: Conversely, SEKI mark these sorts of things as "Class 1" aka marginally developed (or undeveloped) and leaves a line indicating the route. Wallace/Wrights Lakes basins are good examples of official trails in this state. This way some amount of information conveyed about the map accuracy. "Class 1" trails are gray, "Class 2" and "Class 3" are black:

In reference to the first post and "how the trail up to the Trail Lakes has lots of switchbacks that are not shown on the topo" - there's an easy answer to that. That trail has been re-engineered since the Topo was printed. The new trail is wider and has a lot more switchbacks, I imagine for pack trains and erosion control.

The old trail is pretty much as you see printed. It's more direct and scenic and fun to follow. There's a bunch of old rock work. NW of Trail Lakes it passes a few giant old campsites. It joins the new trail in spots and crosses it a few times. The trails finally merge shortly before you hit Golden Creek, just like on your map.

I suspect the trail heading up from Trail Lake to the NE has also been rebuilt, since it's long and boring and often covered with poop. There are a couple ways to get around that.

This is such fun pre-backpacking stuff! Thanks Dave!

oh hey, it's enigmo81

It is interesting how much more direct old trails were - I noticed switchbacks being put in on the west side of kearsarge that seem unnecessary last summer as the main trail isn't at a very steep grade at that point, but I imagine it's for erosion control due to the sheer number of boots on it. I'll have to keep an eye out for the old golden creek trail - it is interesting when new and old trails can have similar weights, I end up bouncing around a bit in humphreys basin, and got a little bemused on piute creek south of turret creek (ended up doing the older more direct route there).

erutan wrote: ↑Wed Mar 31, 2021 4:26 pm oh hey, it's enigmo81

It is interesting how much more direct old trails were - I noticed switchbacks being put in on the west side of kearsarge that seem unnecessary last summer as the main trail isn't at a very steep grade at that point, but I imagine it's for erosion control due to the sheer number of boots on it.

howdy not surprised to see ya here . from what I can see on Google Earth the west side switchbacks near the pass first appear in 2009, before that it looks like a straight shot down a ways. pretty recent as far as things go. we bumped into a survey crew there a few years back putting in stakes, they mentioned they were going to redo them (I didn't ask why, probably should have)... maybe they were done poorly in the first place? ten years seems awfully short for major rework.

the trail on the east side looks like it was devoid of switchbacks for a long time. the old trail is still visible (old Starr maps also imply it was fairly straight), however it looks like the work was done before the mid 80s. both sides are pretty sandy tho so I imagine it's for erosion and not just for the sake of adding pointless switchbacks.

Heh, yeah my partner is from the east coast (and lived 7 years in MT), she thinks switchbacks are stupid and would rather just walk a couple thousand feet straight up heh. She hasn't been up Forester yet, but even doing Glen she'll reluctantly accede it's better than just going straight up given the looseness of terrain.

I find it fascinating how trails change over time - from the early first nations / native americans to the sheepherders and cavalry to the CCC / NFS trails and then how those have evolved over time. It's always really fun stumbling across a fading packer route or old stonework pre USGS maps and wondering about the history of it. There's a digital gap between the 1930 maps and USGS that it'd be fun to fill in... if nothing else old trails give ideas for XC routes.